Calender with different roll sizes



Feb. 6, 1968 R. c. SEANOR ETAL 3,366,992

CALENDER WITH DIFFERENT ROLL SIZES Filed Oct. 22, 1965 REX C. SEANORVERETT PERLBERG United States Patent O 3,366,992 CALENDER WITH DIFFERENTROLL SIZES Rex C. Seanor, Akron, Ohio, and S Everett Perlberg,

Fairlawn, NJ., assignors to Adamson United Company, Akron, Ohio, acorporation of Ohio Filed Get. 22, 1965, Ser. No. 502,031 3 Claims. (Cl.18-2) ABSTRACT OF THE DISCLOSURE An inverted L calender characterized bythe middle roll of the calender having a reduced diameter in relation tothe top and bottom rolls.

This invention relates to a calender for sheeting plastic, rubber, andthe like into relatively thin continuously moving webs, or performingother calendering operations, in which small diameter calender rolls areused in one or more positions of the calender in conjunction with largerdiameter calender rolls.

Heretofore, calenders of the standard inverted L-shape have beencomposed of four calender rolls having substantially equal diameters.The calender rolls are large and heavy and are expensive to produce andinstall. The large diameter calender rolls, due to their large surfacearea, also tend to cause a frictional heat buildup when run forcontinuous periods and this can result in scorching the material to beworked. Usually some type of water or liquid cooling is employedinternally of the rolls to prevent or control this frictional heatbuildup but such a system is not always effective, and may be costly.The standard inverted L calender also requires a large power input todrive the calender rolls and this creates high production costs.

It is the general object of the present invention to avoid and overcomethe stated and other difliculties of prior art practices by providing aninverted L-shaped or other calender in which small diameter calenderrolls are used in conjunction with large diameter calender rolls. Thispermits the calender to be operated with reduced power input since thehorsepower or mechanical energy needed to form the web between thecalender rolls is lowered.

Another object of the present invention is to provide an invertedL-calender wherein the material worked is less subject to scorchingbecause of frictional heat buildups.

Another important object of the invention is to provide a calender inwhich at least two of the bites provided by the calender rolls areformed by a large diameter calender roll and a small diameter calenderroll with the small diameter calender roll being held against deflectionfrom the bite by an adjacent large diameter calender roll. Reducing thedeflection of the calender rolls produces the web at a more uniformgauge the full width of the web and reduces or eliminates correctivemeasures of gauge control, such as roll crown, roll bending, rollcrossing, and the like.

The foregoing objects of the invention, and other objects which willbecome apparent as the description proceeds, are achieved by providingthe combination in a calender for sheeting plastic webs and the like ofa plurality of calender rolls forming at least three bites, at least twoof the bites being formed by a large diameter calender roll and a smalldiameter calender roll and wherein the small diameter calender roll isheld against deflection from the two bites by a large diameter calenderroll.

For a better understanding of the invention, reference should be had tothe accompanying drawings wherein:

FIG. 1 is a diagrammatic side elevation of a typical in- 3,366,992Patented Feb. 6, 1968 verted L calender in which smaller diameter rollshave incorporated in accordance with the invention;

FIG. 2 also is a view similar to FIG. 1 but of a modification of theinvention.

FIG. 3 is a view similar to FIG. 1 but showing another embodiment of theinvention.

FIG. 4 is an enlarged, fragmentary diagrammatic illustration comparingthe resultant forces created by equal diameter calender rolls working ona web and a large and small diameter calender rolls working on a web.

In the drawings, and looking particularly at FIG. 1, the numeral 10generally indicates an inverted L calender in which the four calenderrolls are positioned in the usual relationship with each other. Forpurposes of clarification and convenience, the offset roll 12 isreferred to as being in the number one position, top roll 14 is referredto as being in the number two position, middle roll 16 is referred to asbeing in the number three position, and bottom roll 18 is referred to asbeing in the number four position.

In the usual workings in an inverted L calender, the material M to beworked is fed between the #1 and #2 rolls which take a bite on thematerial to form web W (illustrated with an exaggerated thickness); theweb W next passes between the #2 and #3 rolls with extra material M atthe roll bite; the web W then passes between the #3 and #4 rolls withextra material M at the roll bite, and the web W then passing around the#4 roll and over a typical stripping roll 20 in the direction of thearrow. Note that roll #3 is supported against deflection by both rolls#2 and #4 whereby lateral gauge of the Web W is held substantiallyuniform.

' Referring to FIG. 4, as the material M is operated upon at the biteformed by the equal diameter calender rollers 10a and 12a to produce WebW, the material M creates forces acting in upward and downwarddirections which tends to push the rollers 10a and 12a apart, and whichforces resist rotation of the rolls in the direction of the arrows. Theresultant force can be graphed diagrammatically and since it acts onboth roller 12a and 10a, the force has only been shown in detail onroller 10a. This force graph is represented by line AB with the centerpoint of the force F acting upwardly from point 0. This force F or thecomponent thereof acting towards the roll axis tends to push thecalender roll 10a away from calender roll 12a and tends to bend roll10a. In addition, force F acts on moment radius R to oppose the turningof roll 10a in the direction of the arrow. The greater this resistiveforce (FXR), the higher the frictional heat buildup of the calender.

When a smaller diameter calender roll 10b is used with calender roll 12ato take a bite on the material M (the smaller diameter calender roll1012 indicated by the dotted lines in FIG. 4), another force graph canbe plotted, this one being indicated by the line A'B with the center ofthe resultant force being located at 0. This upwardly acting resultantforce, indicated by F, is less than the force F, and works on theshorter radius R. Accordingly, the power required to rotate roll 10b andto overcome F' R is definitely less than the power to rotate roll 10aand to overcome FXR. The smaller diameter calender roll ltlb permits thecalender to be run with less frictional heat buildup and a smallerhorsepower input. It is important to note that although the smallerdiameter calender roll enables the calender to be run with lesshorsepower input and thus greater efficiency, the quantity and qualityof the web produced is not lowered, and usually is improved.

It has been stated above that roll #3 in FIG. 1 is supported by roll #2and roll #4. Further, it will be recognized that there are less rollbending pressures on rolls #2 and #4 than if roll #3 were of the samesize as rolls #2 and #4.

3 In the form of the invention of FIG. 2, the calender roll 16b is ofreduced diameter but the calender roll 12b is of equal diameter with theremaining two calender rolls 14b and 18b FIG. 3 illustrates that thecalender roll 18c occupying the #4 position, can be of an extra largediameter greater than calender rolls 12c and 146. This positioning ofthe calender rolls tends to reduce the deflection of calender roll 16cin the #3 position when the web passes between the calender rolls in the#2 and #3 positions, and the calender rolls in the #3 and #4 positions.

The forms of the invention as shown in FIGS. 2 and 3 operate with atleast certain of the advantages of the apparatus of FIG. 1.

Throughout the specification and claims the terms large, extra large,and small are intended to define and cover combinations wherein thesmall diameter roll is between about 50% and about 75%, and usuallyabout 66% of the diameter of the large roll. The large diameter roll isbetween about 60% and about 90% of the extra large diameter roll, andusually about 75%. In a typical calender designed in accord with theinvention, the diameter of the large roll was 32" and the diameter ofthe small roll was 20".

While a certain representative embodiment and details have been shownfor the purpose of illustrating the invention, it will be apparent tothose skilled in this art that various changes and modifications may bemade therein without departing from the spirit or scope of theinvention.

What is claimed is:

1. An inverted L-shaped calender comprising four calender rolls formingthree bites, wherein the #3 position roll has a diameter betweenone-half and three-quarters the size of the #1 and #2 position rolls andthe #4 position roll has a diameter between one third and one-half timesgreater than the #1 and #2 position rolls and wherein the small diameterroll in the #3 position is held against deflection from the two bites bythe adjacent large diameter rolls.

2. The combination in an inverted L calender for sheeting plastic,rubber and the like into a web of a plurality of calender rolls formingat least three bites, at least two of the bites being formed by arelatively large diameter calender roll and a relatively small diameter#3 calender roll and wherein the small diameter #3 calender roll is heldagainst deflection from the two bites by a large diameter calender roll,the #3 position roll having a diameter of between about one-half andthree-quarters the diameter of the #2 position roll, the calender havingless frictional heat build-up than calenders with equal size rollstherein comparable to said large diameter roll whereby the roll speed insaid L calender can be increased above that of the comparable calenderWithout exceeding the critical temperature of the material beingprocessed.

3. An inverted L calender for forming webs characterized by the middleroll having a reduced diameter in relation to the top roll and thebottom roll wherein the smaller diameter middle roll is held againstdeflection by the larger diameter bottom roll from the bite formed withthe top roll and, conversely, is held against deflection by the largediameter top roll from the bit formed with the bottom roll, and whereinthe offset roll has a reduced diameter in relation to the top roll.

References Cited UNITED STATES PATENTS 735,175 4/1903 Torrance -462748,593 1/1904 Eek 100162 1,575,539 3/ 1926 Butterworth. 1,930,873 10/1933 Brewster 182 2,525,744 10/1950 Willshaw 182 2,815,531 12/1957Stewart 18-2 WILLIAM J. STEPHENSON, Primary Examiner.

